As wind turbines become increasingly widespread, increased demands are also placed on their behavior on the grid. This also applies to the behavior of the wind turbine in the case of line faults, in particular in the case of the occurrence of overvoltages or peak voltages. Until now, wind turbines have often been disconnected in the event of the occurrence of peak voltages owing to intrinsic protection. However, such a behavior in respect of grid compatibility will no longer be fully accepted in future. It is already demanded that wind turbines tolerate overvoltages up to a value of 130% of the rated voltage. In future, increased demands are also to be expected, at least in some countries.
Conventional wind turbines do not have sufficient reserves for correspondingly increased demands in respect of the overvoltage. Although it is possible in principle to give the current-conducting components and in particular the converter higher power ratings since in this case excess powers of approximately 25% need to be taken into consideration, this results in considerable increases in respect of physical size and installation costs of the converter. Moreover, such an enlargement of the converter often makes a new design of the wind turbine and its electrical system as a whole necessary. The complexity is thus further increased.